LAUSR

The reaction between tetracycline and alkaline permanganate was investigated by combining experimental and computational methods. The kinetics was initially studied using a stopped-flow technique and was found to be first-order in tetracycline and permanganate. The second-order rate constant was positive linearly dependent on the concentration of hydroxyl ion (0.01–0.10 M), indicating the presence of base catalysis. By construction of the Eyring plots in the range of 293–308 K, a lower activation barrier ((14.89 ± 0.44) kcal mol–1) was obtained at 298 K for the base-catalyzed pathway compared with that ((17.72 ± 1.84) kcal mol–1) for the uncatalyzed pathway. The effect of ionic strength further suggested the existence of a complex with higher charge and reactivity. It is confirmed by the theoretical analysis that the hydroxyl ion could attract the proton of tetracycline toward itself to form a complex-like structure with a highly reactive phenolate-type moiety. The highest occupied molecular orbital of te...